Conservation of access network bandwidth during multiuser call connections in a broadband telephony network

ABSTRACT

A broadband telephony network changes a number of users in a multiuser call. The network initially has active users. Each initial active user has a one-way connection as an origin and a one-way connection as a destination. In response to a change in the number of users, for each active user maintaining an active status, the destination of one of the connections where that active user is the origin is changed while that active user remains as that connection&#39;s origin.

BACKGROUND

[0001] The invention generally relates to broadband telephony networks.In particular, the invention relates to routing telephony connections ina broadband network.

[0002]FIG. 1 illustrates a telephony network 10. Telephone users of thebroadband network use telephones 12 ₁ to 12 _(n) connected tocommunication gateways (CGs), 14 ₁ to 14 _(m), to make telephone calls.The CGs 14 ₁ to 14 _(m) are used as an interface between the telephones12 ₁ to 12 _(n) and the rest of the network 10.

[0003] The CGs 14 ₁ to 14 _(m) are connected to an Internet protocol(IP) network 18 through a cable modem termination system 16 interfacingbetween the CGs 14 ₁ to 14 _(m) and the IP network 18. The IP network 18transfers packets of data. Each packet is sent in an assigned mini-slotof a frame in the network 18. Each packet carries communication data,such as encoded voice data, and overhead and routing data, such as adestination address.

[0004] The IP network is connected to the public switched telephonenetwork (PSTN) 28 via a PSTN/IP network gateway 26. Telephone users 30 ₁to 30 _(j) using telephones outside the broadband network cancommunicate with broadband network telephone users 12 ₁ to 12 _(n)through the PSTN 28.

[0005] The simplified hardware of a CG 14 ₁ to 14 _(m) is shown in FIG.2. The CG 14 ₁ to 14 _(m) has an RF connector 32 to receive RF signalsfrom and transmit RF signals over the broadband network 10. Atuner/amplifier 34 and a cable modem 36 are used to convert the receivedRF signals into digital baseband signals and digital baseband signalsinto RF signals for transmission. The CG 14 ₁ to 14 _(m) also has adigital signal processor (DSP) 38 and codec 40 for processing voicesignals. A processor 42 along with a random access memory (RAM) 44 andnon-volatile memory (NVMem) 46 are used to perform many functions, suchas performing commands as directed by the call management system 20.

[0006] To handle the overhead functions of the IP network 18, a networkmanagement system 22, an operating support system 24 and a callmanagement system 20 are used. The call management system 20, “callagent”, controls telephony calls sent through the network 18. If a callor a multiparty call extends over multiple networks call managers 20 inthe different networks are used to facilitate communications between thenetworks. Typically, the party placing the call is the “control party”and its call manager 20 controls the call connections. Additionally,depending on the size and design of a network a single network may haveone or multiple call managers 20.

[0007] The simplified hardware of a call management system 20 is shownin FIG. 3. The call management system 20 comprises a call agent and a RFconnector 48. The call agent 48 controls various functions of callmanagement system 20 and interacts with other modules 22,24. Callsignaling 50 sends commands to control components of the network, suchas the CGs 14 ₁ to 14 _(m). Other components of the call managementsystem 20 for use in performing its functions are the communicationsstacks 52, network interface module (NIM) 54, processor 58, RAM 60,non-volatile memory 62 and permanent storage 56.

[0008] One call agent function is to establish telephone connectionsbetween the telephone users 12 ₁ to 12 _(n). FIGS. 4a to 4 d are a flowchart and illustrations of establishing a three-way telephone call. Asshown in FIG. 4b, a bi-directional connection is established betweentelephone user 1, T₁ 12 ₁ and telephone user 2, T₂ 12 ₂, 66. Eachbi-directional connection has two opposing one-way connections. Eachone-way connection in the network has an origin, a destination and atleast one assigned mini-slot. Based on the bandwidth required for aconnection and a network's allocation rules, multiple mini-slots may beassigned to a connection.

[0009] T₁ 12 ₁ initiates a three-way call by placing T₂ 12 ₂ “on hold”and placing a call to telephone user 3, T₃ 12 ₃. As shown in FIG. 4c,the “on hold” connection between T₁ 12 ₁ and T₂ 12 ₂ is maintained butinactive (as shown by dashed line). A bi-directional connection isestablished between T₁ 12 ₁ and T₃ 12 ₃, 68. When T₁ 12 ₁ initiates athree-way call, both bi-directional connections (T₁/T₂ and T₁/T₃) arebroken, deleted. Simultaneously, three new bi-directional connectionsare established to a network bridge 64 (T₁/bridge, T₂/bridge andT₃/bridge), 70. The network bridge 64 can be located anywhere within thetelephony network 10, which includes the broadband network, the IPnetwork 18 and the PSTN 28. One function of the network bridge 64 is tomix the messages from multiple users to be sent to one of the users. Toillustrate for user T₂ 12 ₂, all three users T₁ 12 ₁, T₂ 12 ₂ and T₃ 12₃ send messages to the bridge 64. The bridge 64 sends the combinedmessages of T₁ 12 ₁ and T₃ 12 ₃ without T₂'s message to T₂ 12 ₂. Usingthe network bridge 64 eliminates the need for the telephone users 12 ₁to 12 _(n) to mix voice signals. For instance, T₁ 12 ₁ does not need tosend T₃ 12 ₃ both T₁'s and T₂'s mixed voice signals.

[0010] Using the network bridge 64 also has drawbacks. When the T₁/T₂and T₁/T₃ connections are broken, the network 10 may not have adequatebandwidth to establish the three new bi-directional connections.Initially, there are four one-way connections (two bi-directionalconnections) between T₁ 12 ₁, T₂ 12 ₂ and T₃ 12 ₃. After establishingconnections to the bridge 64, six (6) one-way connections (threebi-directional connections) are established requiring additionalbandwidth for the two extra one-way connections. Furthermore, due to themixing at the bridge 64, the connections originating from the bridge 64may use higher rate voice coders requiring additional bandwidth. As aresult, all of the connections may be lost. Accordingly, it is desirableto have alternate approaches to multi-user connection.

SUMMARY

[0011] A broadband telephony network changes a number of users in amultiuser call. The network initially has active users. Each initialactive user has a one-way connection as an origin and a one-wayconnection as a destination. In response to a change in the number ofusers, for each active user maintaining an active status, thedestination of one of the connections where that active user is theorigin is changed while that active user remains as that connection'sorigin.

BRIEF DESCRIPTION OF THE DRAWING(S)

[0012]FIG. 1 is an illustration of a broadband telephony network.

[0013]FIG. 2 is an illustration of a communication gateway.

[0014]FIG. 3 is an illustration of a call management system/call agent.

[0015]FIG. 4 is a flow chart of establishing a related art three-waycall.

[0016]FIGS. 4b to 4 d are illustrations of establishing a related artthree-way call.

[0017]FIG. 5a is a flow chart of three-way call connection.

[0018]FIGS. 5b to 5 f are illustrations of a three-way call connection.

[0019]FIG. 6a is a flow chart of a multiuser call connection.

[0020]FIGS. 6b to 6 f are illustrations of a multiuser call connection.

[0021]FIG. 7a is a flow chart of dropping a user from a three-way call.

[0022]FIGS. 7b to 7 d are illustrations of dropping a user from athree-way call.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0023]FIGS. 5a to 5 f are a flow chart and illustrations of a three-waycall connection. T₁ 12 ₁ and T₂ 12 ₂ are initially communicating and abi-directional connection exists between T₁ 12 ₁ and T₂ 12 ₂, as shownin FIG. 5b, 72. T₁ 12 ₁ places T₂ 12 ₂ “on hold” and that connection ismaintained but made inactive, as shown by the dashed lines in FIG. 5c.T₁ 12 ₁ initiates a call with T₃ 12 ₃. A new bi-directional connectionbetween T₁ 12 ₁ and T₃ 12 ₃ is established as shown in FIG. 5c, 74.

[0024] To initiate a three-way call, T₁ 12 ₁ sends a signal. Thebi-directional connections between T₁ 12 ₁, T₂ 12 ₂, and T₃ 12 ₃ aremaintained but temporarily inactive. The network bridge 64 establishes aone-way connection from the bridge 64 to each telephone user 12 ₁ to 12₃ as shown in FIG. 5d, 76. As shown in FIG. 5e, the connectionsoriginating from each user 12 ₁ to 12 ₃ are rerouted to the bridge, 78.The one-way connection from T₁ 12 ₁ to T₃ 12 ₃ is routed to terminate atthe bridge 64. Likewise, the one-way connections from T₂ 12 ₂ to T₁ 12 ₁and T₃ 12 ₃ to T₁ 12 ₁ are rerouted to terminate at the bridge 64. Theprevious routing for the connections is shown by a dotted line. Sincethe user 12 ₁ to 12 ₃ of each rerouted connection is the same, thebandwidth requirements of each rerouted connection are the same. Toreroute these connections, the call agent 20 simply directs that thedestination addresses in the packets associated with the reroutedconnections be changed. Voice communication between all three users 12 ₁to 12 ₃ is then achieved through the bi-directional connections betweenthe bridge 64 and each user 12 ₁ to 12 ₃. After the rerouting iscompleted, the unnecessary one-way connection between T₁ 12 ₁ and one ofthe other users, such as T₂ 12 ₂, is deleted, as shown in FIG. 5f as adotted line, 80.

[0025] The call agent 20 directs the rerouting of calls, theestablishing and deleting of connections between the users 12 ₁ to 12 ₃and establishing the bridge 64 using its call signaling 50, processor 58and associated RAM 60 and instructions stored in its NVMem 62. The CG 14₁ to 14 _(m) and bridge 64 perform the routing commands as directed bythe call agent 20. The CGs 14 ₁ to 14 _(m)will receive the downstreamcommands and perform the rerouting of its connections using theirprocessors 42, associated RAM 44 and instructions stored in its NVMem46.

[0026] One advantage to the approach of FIGS. 5a to 5 f is that therouting complexity of the CG 14 ₁ to 14 _(m) is reduced. The CG 14 ₁ to14 _(m) merely changes the destination of its transmitted packetsinstead of being assigned new packets and mini-slots. However, thecomplexity at the call agent 20 is increased due to the increase inrouting.

[0027] If any of the new connections of FIG. 5d cannot be made, theapproach of FIGS. 5a and 5 d allows for a graceful recovery. Since theinitial connections between the users 12 ₁ to 12 ₃ are maintained whilethe bridge 64 establishes one-way connections between it 64 and theusers 12 ₁ to 12 ₃, if any of the new one-way connections can not beestablished, the original connections between the users 12 ₁ to 12 ₃ canbe reactivated. This approach reduces the chance that a call will bedropped.

[0028] One drawback to this approach is for a short period of time,seven one-way connections are required, as shown in FIGS. 5d and 5 e. Asa result, excess bandwidth is allocated for a short period of time. Toeliminate the excess bandwidth allocation, the extra connection can bedeleted at the same time the bridge establishes the three one-wayconnections, such as deleting the extra T₁ to T₂ connection, as in FIG.5f. As a result, only a maximum of six (6) one-way connections arerequired. However, only a graceful recovery between two of the users,such as T₁/T₃, is readily achieved. Due to the deleted extra connection,a graceful recovery between the other users, such as T₁/T₂, may not bepossible. Accordingly, a trade-off between ease of recovery and allottedbandwidth is achieved.

[0029] The approach of FIGS. 5a to 5 f can be applied to more than athree-way call, such as an n-way call. Illustrations and a flow chart ofan n-way call using the approach of FIGS. 5a to 5 f are shown in FIGS.6a to 6 f. T₁ desires to add an n^(th) user, T_(n) 12 _(n), to anexisting n−1-way call. As shown in FIG. 6c, an n−1-way call withconnections to the bridge 64 exists. T₁ 12 ₁ temporarily drops out ofthe n−1-way call, such as by performing a “hook flash,” and establishesa bi-directional connection to T_(n) 12 _(n), as shown in FIG. 6c, 84.T₁ 12 ₁ initiates adding T_(n) 12 _(n) to the call, such as by a “hookflash” signal. A one-way connection from the bridge 64 to T_(n) 12 _(n)is established, as shown in FIG. 6d, 86. As shown in FIG. 6e, theone-way connection from T_(n) to T₁ is rerouted to terminate at thebridge 64, 88. Subsequently, the excess connection is deleted, as shownin FIG. 6f, 90.

[0030]FIGS. 7a to 7 d are a flow chart and illustrations for dropping auser from a three-way call, such as T₂ 12 ₂. As shown in FIG. 7b, abi-directional connection exists between each user, T₁ 12 ₁, T₂ 12 ₂ andT₃ 12 ₃, and the bridge 64, 92. After T₂ 12 ₂ hangs up the one-wayconnections from the bridge 64 to T₁ 12 ₁ and T₃ 12 ₃ are deleted, asshown in FIG. 7c, 94. To connect T₁ 12 ₁ to T₃ 12 ₃, as shown in FIG.7d, the connection from T₁ 12 ₁ to the bridge 64 is rerouted toterminate at T₃ 12 ₃ and the connection from T₃ 12 ₃ to the bridge 64 isrerouted to terminate at T₁ 12 ₁. Since the bandwidth for theconnections originating from each user 12 ₁, 12 ₃ are unchanged, thererouting is simply performed by changing the destination address of thepackets associated with the connections.

What is claimed is:
 1. A method for changing a number of active users ina multiuser call in a broadband telephony network, the network capableof establishing and deleting connections between the users, the methodcomprising: for each user initially in an active status, providing aone-way connection with that initial active user as the destination anda one-way connection with that initial active user as an origin;changing a number of active users in the multiuser call; in response tothe user number change, for one of the users having the active status,changing the destination of one of that maintained one active user'sconnections where that one active user is the origin while that activeuser remains as that one connection's origin; and establishing andmaintaining one-way connections as needed so that each of the activeusers having the active status has a one-way connection where thatactive user is an origin and that active user is a destination.
 2. Themethod of claim 1 wherein after the establishing and maintaining one-wayconnections as needed, deleting any unused one-way connections.
 3. Themethod of claim 1 wherein the establishing one-way connections isperformed prior to changing the destinations.
 4. The method of claim 1wherein the destination changing connection maintains a bandwidthassociated with the destination changing connection.
 5. The method ofclaim 1 wherein the destination changing connection maintaining anassigned mini-slot associated with the destination changing connection.6. The method of claim 1 wherein the destination changing connectionchanges its destination by changing a destination address associatedwith packets of the destination changing connection
 7. A network forchanging a number of active users in a multiuser call, the networkcompromises: a plurality of communication gateways of a broadbandnetwork, each gateway capable of participating in a multiuser call witha changing number of users, each gateway compromises: a processor forreceiving commands from a call agent and changing characteristics ofconnections associated with the commands gateway in response tocommands; and the call agent for producing commands associated withconnections of the multiuser call and in response to the change in thenumber of users, the commands direct one of the communication gatewaysto change the destination of a connection of the one gateway where thatone gateway is maintained as an origin of that one gateway connection.8. The network of claim 7 wherein the destination changing connectionmaintains a bandwidth associated with the destination changingconnection.
 9. The network of claim 7 wherein the destination changingmaintains an assigned mini-slot associated with the destination changingconnection.
 10. The network of claim 7 wherein the destination change isperformed by changing a destination address associated with packets ofthat one gateway connection.
 11. A call agent for changing a number ofusers in a multiuser call, the call agent comprising: a call signalingblock for producing commands associated with connections of themultiuser call, in response to the change in the number of users, thecommands direct one user of the multiuser call to change the destinationof a connection of the one user where that one user is maintained as anorigin of that connection.
 12. The call agent of claim 11 wherein thedestination changing connection maintains a bandwidth associated withthe destination changing connection.
 13. The call agent of claim 11wherein the destination changing connection maintains an assignedmini-slot associated with the destination changing connection.
 14. Thecall agent of claim 11 wherein the destination changing connectionchanges its destination by changing a destination address associatedwith packets of the destination changing connection.
 15. A communicationgateway of a broadband telephony network, the communications gatewaycapable of participating in a multiuser call with a changing number ofusers, a call agent associated with the communication gateway producescommands for directing connections involving the communication gateway,the communication gateway comprising: an RF connector and associatedtuner for receiving commands and messages over connections of thenetwork and for transmitting messages over connections of the network;and a processor having an input configured to receive the receivedcommands and in response to receiving commands associated with thenumber of users change, changing a destination of messages transmittedby the communication gateway over one of the transmitting connectionswhile maintaining other characteristics of the connection.
 16. Thecommunication gateway of claim 14 wherein one of the othercharacteristics is a bandwidth of the one connection.
 17. Thecommunication gateway of claim 14 wherein one of the othercharacteristics is an assigned mini-slot associated with the oneconnection.
 18. The communication gateway of claim 14 wherein thedestination change of the one connection is performed by changing adestination address associated with packets of the one connection.